Need help on executing chroot command
 

Hi all,

I am trying to execute chroot command by changing the root in ubuntu machine.

Let me explain the situation.
I was mounted an ubuntu image in /mnt/ubuntu directory using follwoing command :
mount /dev/mapper/loop1p1 /mnt/ubuntu
it was successfully executed. so finally i want to install new package in the ubuntu image which is ther /mnt/ubuntu . In order to execute the chroot command i was setting chroot environment by following commands:

mount -o bind /dev /mnt/ubuntu/dev
mount -o bind /proc /mnt/ubuntu/proc
mount -o bind /sys /mnt/ubuntu/sys

The above commands also executing successfully.
finally i am trying to install linux-image kernel package on mounted image which is there in /mnt/ubuntu.

chroot /mnt/ubuntu dpkg -i tmp/linux-image.deb
chroot: failed to run command `dpkg': No such file or directory

this is the error i am getting .
please help me.

regards,
Prasad.

I think you would have to mount -o bind whatever directory dpkg is in.

Try passing the location of dpkg explicitly. Otherwise, try chrooting into it and executing the command manually so you can see what's happening.

Hi T3slider,

I have tried both the cases which you mentioned in the comments.

chroot /mnt/ubuntu /usr/bin/dpkg /tmp/linux-image.deb
chroot: failed to run command `/usr/bin/dpkg': No such file or directory

second option :
first i have this command . this command it self showing error.
chroot /mnt/ubuntu
chroot: failed to run command `/bin/bash': No such file or directory

regards,
prasad.

I think you need to have a look in /mnt/ubuntu when it's mounted -- it seems it does not contain files necessary for chrooting (or booting). Either some important directory is not being mounted, or you do not have a complete Ubuntu install on /dev/mapper/loop1p1.

Today i will change the ubuntu image and try again.

chroot /mnt/ubuntu it self fails
 

hi ,

i am unable to execute the chroot /mnt/ubuntu command this command showing following error.

chroot: failed to run command `/bin/bash': No such file or directory

please help me.

regards,
Prasad.

As said before, check the directory for existance of /bin/bash, it seems that you don't have a fully functional install in that image.

first i have taken one ubuntu image which is ubuntu-flat.vmdk .
this i have converted into raw format using qemu converter

qemu-img convert ubuntu-flat.vmdk -O raw ubuntu-flat.raw

i find out the free loop device . suppose i have taken loop5 in /dev/loop5 location.

losetup /dev/loop5 ubuntu-flat.raw.
kpartx -a /dev/loop5
mkdir /mnt/ubuntu
mount /dev/mapper/loop5p1 /mnt/ubuntu
mount -o bind /dev /mnt/ubuntu/dev (for this befor i have created dev directory in the /mnt/ubuntu location manually)
mount -o bind /proc /mnt/ubuntu/proc(proc also created before executing)
mount -o bind /sys /mnt/ubuntu/sys(sys also created before executing)

next i am trying to execute
chroot /mnt/ubuntu dpkg -i /tmp/somepackage.deb

Problems coming now as i mentioned above.

so is there any wrong procedure i am following .

regards,
prasad

After you mount the Ubuntu image, just check, using ls, if /bin/bash is present in the image:

its not there in that image.

ls /mnt/server/bin/bash
ls: cannot access /mnt/server/bin/bash: No such file or directory

Then the image is most likely not a complete system image and chrooting into it won't work.

yes, My image gets corrupted and i have taken new image.I followed same procedure as i written in previous.
This time i am able to perform chroot command.